President Cristina Fernandez, who has pushed for a greater state role in businesses and the economy, is seen losing control of Congress in the vote to renew half of the lower house and a third of the Senate.

Since the newly elected deputies and senators will not be seated until December, investors are uncertain about the second half of the year, and some believe Fernandez could use those months to push an interventionist policy.

In trade between foreign exchange houses, as measured by Reuters, the peso ARSB= softened by 0.38 percent to 3.9000/3.9050 per dollar, its weakest level since June 2002.